1. Field of the Invention
This invention relates to a light emitting device to be used for the light source or the display of OA instruments, etc.
2. Related Background Art
Heretofore, there have been reported various materials for constituting the light emitting layers of light emitting devices. Among them, non-single crystalline silicon containing hydrogen atoms (hereinafter written as "non-Si:H") as described in, for example, Appl. Phys. Lett. 29 (1976), PP. 620-622, J. I. Pankou, D. E. Carlson or Jpn. J. Appl. Phys 21 (1982) pp. 473-475, K. Takahashi et al is one of the materials which are attracting attention, because semiconductor engineering similarly as in the case of single crystalline silicon is applicable and also there is the possibility that some potential characteristics may be excellent, etc.
The constitution of the light emitting device in which the non-Si:H is used as the light emitting material described in the above cited references has a homo-junction having a P-type conductive layer containing a P-type impurity (P layer), a layer containing none of P-type and N-type impurities (non doped) layer) and an N-type conductive layer containing an N-type impurity (N layer) laminated.
However, in the light emitting device reported in the prior art with such a constitution, no luminescence in the visible light region with sufficient luminescent quantity has been obtained. In addition, the luminescent intensity is weak with its life being short, and also stability of luminescent characteristics is lacking. Thus, there remain a large number of drawbacks to be improved. As one idea to improve the above drawbacks, there has been an attempt to obtain luminesence in the visible wavelength region by enlarging the optical band gap by addition of carbon atoms to non-Si:H, but practically problems still remain, and there has been obtained no material which can be industrialized for the light source device or the display device to be used in OA instruments, etc.